The hydraulic oil temperature is closely monitored by the ECU, which allows it to make on-the-fly adjustments to avoid overheating. If there is an unusually high-voltage signal on the hydraulic oil temperature sensor circuit, this temperature data will be compromised, and a P0940 DTC will be triggered.
How Serious is the Code?
The P0940 diagnostic trouble code is quite serious, because it means the ECU does not know the current temperature of the hydraulic oil. This can obviously lead to overheating, and that can result in serious/expensive damage.
Symptoms of a P0940 include:
- Check engine light
- Erratic vehicle behavior
- Limp Mode
- Damaged/corroded wiring and/or connectors
- Faulty hydraulic oil temperature sensor
- Low hydraulic fluid
- Dirty hydraulic fluid/filter
How to Diagnose the Code?
Diagnosing a P0940 OBDII trouble code, should start with a check of the condition of the hydraulic oil (if it’s dirty, it will need to be changed). The wiring and connectors along the hydraulic oil temperature sensor circuit will then need to be closely examined for signs of damaged wires, and corroded or broken connectors. This sensor itself may also need to be tested, along with possibly the ECU.
What Repairs Will Fix P0940?
- Repair damaged wiring and/or connectors
- Replace hydraulic oil temperature sensor
- Change hydraulic fluid
- Reprogram or replace ECU